# [LeetCode] 800. Similar RGB Color 类似的红绿蓝颜色

2021年09月15日 阅读数：2

In the following, every capital letter represents some hexadecimal digit from `0` to `f`.html

The red-green-blue color `"#AABBCC"` can be written as `"#ABC"` in shorthand.  For example, `"#15c"` is shorthand for the color `"#1155cc"`.java

Now, say the similarity between two colors `"#ABCDEF"` and `"#UVWXYZ"` is `-(AB - UV)^2 - (CD - WX)^2 - (EF - YZ)^2`.python

Given the color `"#ABCDEF"`, return a 7 character color that is most similar to `#ABCDEF`, and has a shorthand (that is, it can be represented as some `"#XYZ"`git

```Example 1:
Input: color = "#09f166"
Output: "#11ee66"
Explanation:
The similarity is -(0x09 - 0x11)^2 -(0xf1 - 0xee)^2 - (0x66 - 0x66)^2 = -64 -9 -0 = -73.
This is the highest among any shorthand color.
```

Note:api

• `color` is a string of length `7`.
• `color` is a valid RGB color: for `i > 0``color[i]` is a hexadecimal digit from `0` to `f`
• Any answer which has the same (highest) similarity as the best answer will be accepted.
• All inputs and outputs should use lowercase letters, and the output is 7 characters.

Java:  暴力htm

```class Solution:
def similarRGB(self, color):
"""
:type color: str
:rtype: str
"""
r,g,b = int(color[1:3],16), int(color[3:5],16), int(color[5:7],16)
a = ['00','11','22','33','44','55','66','77','88','99','aa','bb','cc','dd','ee','ff']
p = [(a[i],a[j],a[k]) for i in range(16) for j in range(16) for k in range(16)]
res, min = '', 9999999
for s in p:
d = (int(s[0],16)-r)**2 + (int(s[1],16)-g)**2 + (int(s[2],16)-b)**2
if min>d:
min=d
res=s
return '#'+''.join(res)
```

Python: 暴力

```class Solution(object):
def similarRGB(self, color):
"""
:type color: str
:rtype: str
"""
ir, ig, ib = (int(color[x: x+2], 16)
for x in (1, 3, 5))
ans = ()
delta = 0x7FFFFFFF
for r in range(16):
for g in range(16):
for b in range(16):
ndelta = sum((ic - c * 17) ** 2
for ic, c in zip((ir, ig, ib), (r, g, b)))
if ndelta < delta:
delta = ndelta
ans = r, g, b
return '#' + ''.join(hex(c)[2] * 2 for c in ans)　```

Python: 解法2 Time:  O(1), Space: O(1)

```class Solution(object):
def similarRGB(self, color):
"""
:type color: str
:rtype: str
"""
def rounding(color):
q, r = divmod(int(color, 16), 17)
if r > 8: q += 1
return '{:02x}'.format(17*q)

return '#' + \
rounding(color[1:3]) + \
rounding(color[3:5]) + \
rounding(color[5:7])　　```

Python:  解法3

```def similarRGB(self, color):
ret = '#'
for i in range(1, 6, 2):
c1, c2 = [int(_) if '0'<=_<='9' else 10+ord(_)-ord('a') for _ in color[i:i+2]]
c = c1+sorted(enumerate([abs((c1*16+c2)-(x*16+x)) for x in [c1-1, c1, c1+1]]), key=lambda _:_[1])[0][0]-1
ret += str(c)*2 if c<=9 else chr(c-10+ord('a'))*2
return ret　　```

C++: 暴力，T: O(3 * 16)  S: O(1)

```class Solution {
public:
string similarRGB(string color) {
const string hex{"0123456789abcdef"};
vector<int> rgb(3, 0);
for (int i = 0; i < 3; ++i)
rgb[i] = hex.find(color[2 * i + 1]) * 16 + hex.find(color[2 * i + 2]);

string ans(7, '#');
for (int i = 0; i < 3; ++i) {
int best = INT_MAX;
for (int j = 0; j < 16; ++j) {
int diff = abs(j * 16 + j - rgb[i]);
if (diff >= best) continue;
best = diff;
ans[2 * i + 1] = ans[2 * i + 2] = hex[j];
}
}
return ans;
}
};
```

C++:

```class Solution {
public:
string similarRGB(string color) {
return "#" + helper(color.substr(1, 2)) + helper(color.substr(3, 2)) + helper(color.substr(5, 2));
}
string helper(string str) {
string dict = "0123456789abcdef";
int num = stoi(str, nullptr, 16);
int idx = num / 17 + (num % 17 > 8 ? 1 : 0);
return string(2, dict[idx]);
}
};
```

C++:

```class Solution {
public:
string similarRGB(string color) {
for (int i = 1; i < color.size(); i += 2) {
int num = stoi(color.substr(i, 2), nullptr, 16);
int idx = num / 17 + (num % 17 > 8 ? 1 : 0);
color[i] = color[i + 1] = (idx > 9) ? (idx - 10 + 'a') : (idx + '0');
}
return color;
}
};
```